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Formula: Fe3+O(OH)
Hydroxide, paramorph of goethite
and feroxyhyte
Crystal System: Orthorhombic
Specific gravity: 4.05 to 4.13 measured, 3.96 calculated
Hardness: 5
Streak: Orange
Colour: Deep red, red-brown
Common impurities: Mn
Environments:
Sedimentary environments
Hydrothermal environments
Lepidocrocite is common in iron ore deposits as a weathering or oxidation product of other iron-bearing minerals,
as a precipitate from ground water and in marine manganese nodules.
Associated minerals include goethite and
pyrite
(HOM).
Localities
The type locality is Zlaté Hory, Jeseník District, Olomouc Region, Czech Republic.
At Johanngeorgenstadt, Erzgebirgskreis, Saxony, Germany, the hydrothermal quartz
- calcite - uraninite veins were
overprinted several times by later hydrothermal activity; the original assemblage was usually seen only in relict form.
Coxcomb quartz was fairly commonly sprinkled with tiny, flake-like
lepidocrocite crystals. Lepidocrocite also overlays scalenohedral
calcite crystals, remaining through the metasomatism of
calcite to dolomite, leaving a strong
brown to reddish colour, particularly in areas rich in pitchblende
(MinRec 55.5.599).
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